Development of PEGylated Cu nanoclusters: A nontoxic, multifunctional colloidal system for bioimaging and peroxide sensing.

This study introduces the development of blue-emitting colloidal Cu NCs through a novel and easy PEGylation method using different functional groups, including -SH and -COOH. The surface functionalization controls the size, cellular toxicity, and emission properties of Cu NCs. The combination of PEG, thiol, and carboxylic groups protects the particle surface from aggregation and oxidation. Among the samples, CAGP (Surface modified Cu NCs with -SH-COOH-PEG combination) emerges as an amazing candidate with the lowest toxicity and enhanced blue emission properties. The bright blue fluorescence emission from Hela cells after treatment with CAGP demonstrated this property. It also has excellent peroxide sensing potential, with a detection limit of 1.4 µM. Because of their excellent bioimaging and peroxide sensing properties, these Cu NCs could be a promising candidate for cellular oxidative stress sensing applications with high clinical relevance.

Sensitization of cancer cells towards Cisplatin and Carboplatin by protein kinase D inhibitors through modulation of ATP7A/B (copper transport ATPases).

Drug resistance of cancer cells is a significant impediment to effective chemotherapy. One primary reason for this is copper exporters - ATPase copper transporting alpha (ATP7A) and ATPase copper transporting beta (ATP7B). These molecular pumps belong to P-type ATPases and dispose off the Platinum (Pt) based anticancer drugs from cancer cells, causing resistance in them. For the disposal of Pt-drugs, copper exporters require phosphorylation mediated by protein kinase D (PKD) for their activation and trafficking. Even though various research works are underway to overcome resistance to anticancer drugs, the role of PKD is mainly ignored. In this study, we have found a significant upregulation of ATP7A and ATP7B in cervical cancer cells (HeLa) and Liver Hepatocellular Carcinoma cells (HepG2) in the presence of Cisplatin or Carboplatin; both at transcriptional as well as translational levels. Interestingly, the expression of ATP7A and ATP7B were significantly downregulated in the presence of a PKD inhibitor (CID2011756), resulting in the reduction of PKD mediated phosphorylation of ATP7A/7B. This causes enhancement of proteasome-mediated degradation of ATP7A/7B and thereby sensitizes the cells towards Cisplatin and Carboplatin. Similarly, the treatment of Cisplatin resistant HepG2 cells with PKD inhibitor causes enhanced sensitivity towards Cisplatin drug. However, the presence of proteasome inhibitor (MG132) reversed the effect of the PKD inhibitor on the expression level of ATP7A/7B, indicating the necessity of phosphorylation for its stability. Hence, we conclude that the combinatorial usage of Cisplatin with drugs targeting PKD can be developed as an effective chemotherapeutic approach to overcome drug resistance.

Development of a paper printed colorimetric sensor based on Cu-Curcumin nanoparticles for evolving point-of-care clinical diagnosis of sodium.

The homeostatic control of Sodium (Na+) ion in the human body assumes paramount relevance owing to its physiological importance. Any deviation from the normal level causes serious health problems like hypernatremia, hyponatremia, stroke, kidney problems etc. Therefore, quantification of Na+ levels in body fluids has significant diagnostic and prognostic importance. However, interfering ions like Potassium ion (K+) is the major hurdle in sodium detection. In this work, we synthesized the clusters of 3-9 nm-sized highly stable and pure Copper nanoparticles surface functionalised with curcumin, through chemical reduction method. Each cluster of particles is encapsulated in a curcumin layer which is clearly visible in TEM images. The results show that these curcumin functionalized Cu NPs (CuC) are highly selective to the colorimetric detection of Na+. The ions like K+, Mg2+ and Zn2+ did not interfere with the Na+ in this sensing technique. Low-cost paper-based sensor strips are fabricated and calibrated for the sensing of sodium in the physiological range and shade cards were developed as a calorimetric guide for estimation of Na+ which makes them ideal point of care diagnostic platform. We demonstrate that the proposed CuC paper strip can be used for detecting Na+ concentration within the whole physiological range in both blood serum and urine.

Green Synthesis of Engineered CdS Nanoparticles with Reduced Cytotoxicity for Enhanced Bioimaging Application.

The modern epoch of semiconductor nanotechnology focuses on its application in biology, especially in medical sciences, to fetch direct benefits to human life. Fabrication of devices for biosensing and bioimaging is a vibrant research topic nowadays. Luminescent quantum dots are the best option to move with, but most of them are toxic to living organisms and hence cannot be utilized for biological applications. Recent publications demonstrate that surface treatment on the nanoparticles leads to enhanced luminescence properties with a drastic reduction in toxicity. The current work introduces surface-modified CdS, prepared via a simple green chemical route with different medicinal leaf extracts as the reaction media. Lower toxicity and multiple emissions in the visible region, observed for the CdS-O.tenuiflorum hybrid structures, make them a better option for future biological applications. Furthermore, the hybrid structure showed enhanced electrical properties, which promises its use in modifying the current optoelectronic devices.

Label Free, Nontoxic Cu-GSH NCs as a Nanoplatform for Cancer Cell Imaging and Subcellular pH Monitoring Modulated by a Specific Inhibitor: Bafilomycin A1.

Metal nanoparticles-based sensors invoked much research attention in the biomedical field, especially in applications involving live cell imaging and monitoring. Here, a simple cost-effective method is adopted to synthesize glutathione coated copper nanoclusters (Cu-GSH NCs) with strong bright red fluorescence (625 nm). The clusters were found to be containing five Cu(0) atoms complexed with one molecule of glutathione (GSH) as evidenced by MALDI-TOF MS analysis. The synthesized Cu-GSH NCs system responds linearly to the pH in the acidic and alkaline ranges with a high degree of in vitro pH reversibility, projecting its potential as a real time pH sensor. Higher intensity emission observed in acidic conditions can be exploited for its employability as cellular organelle markers. The imaging and sensing potential of Cu-GSH NCs in the live human adenocarcinoma cell line, the HeLa cells, was tested. The treatment of HeLa cells for 48 h imparted deep red fluorescence, owing to the lower level of intracellular pH in cancer cells. In contrast, the imaging using normal cell lines (L-132, lung epithelial cell line) showed significantly lower fluorescence intensity as compared to that of HeLa cells. The subcellular pH-dependent fluorescence emission of Cu-GSH NCs was further assessed by treating HeLa cells with proton pump (V-ATPase) inhibitor Bafilomycin A1, which increases the vesicular pH. Interestingly, the fluorescent intensity of HeLa cells decreases with increasing concentration of Bafilomycin A1 in the presence of Cu-GSH NCs, as evidenced by the fluorescence microscopic images and quantitative fluorescent output. Accordingly, the developed Cu-GSH NCs system can be employed as an efficient pH-based bioimaging probe for the detection of cancer cells with an implied potential for the label free subcellular organelle tracking and marking. Importantly, the Cu-GSH NCs can be used for live cell pH imaging owing to their high degree of reversibility in sensing of pH variation.

Cytotoxicity of nanoparticles - Are the size and shape only matters? or the media parameters too?: a study on band engineered ZnS nanoparticles and calculations based on equivolume stress model.

Size dependent cytotoxicity of ZnS nanoparticles (NPs) was investigated in Human embryonic kidney (HEK-293) cell lines by MTT assay. The cells were incubated with varying concentration of ZnS NPs of sizes 4 nm, 10 nm and 25 nm for 48 h under different (cell culture) media viscosity conditions. The results showed that the toxicity is decreased with the particle size while it is negatively correlated with the viscosity of the media. Theoretical calculations were performed, by assuming equivolume stress model and the same is explained with schematics. Similarly, the effect of particle size and shape on toxicity is explained based on the theoretical calculation of the stress. The calculations showed that out of the possible cellular entry mechanisms for the cubic or cage shaped NPs, the highest toxicity is predicted for the entry through the corners while the lowest toxicity is predicted for the entry through the faces. The experimental observations depicting the cytotoxicity as a function of the viscosity of cell culture media was also validated by stress calculations and are found to be consistent. Studies on size and shape dependence of semiconductor NPs like ZnS is rather scarce, while the role of viscosity of cell culture media on the cytotoxicity is being reported for the first time. In summary, the study indicates that the cytotoxicity is an integral function of size and shape of NPs, physical parameters of the cell culture media in addition to the post entry biochemical interactions with the host cell.